1. Field of the Invention
The present invention relates to a process for producing a polyolefin-based resin composition, and more particularly, to a process for producing polyolefin-based resin composition providing film which has a good dispersion of polymer fine particles as an anti-blocking agent to a polyolefin-based resin, and is excellent in appearances such as transparency, see-through feeling, little generation of white spot (called as fish-eye) and the like, and in anti-blocking property.
2. Description of the Related Arts
A polyolefin-based resin film is used for materials for food packaging and textile packaging, and the like, because it is superior in physical properties such as transparency, mechanical property and the like.
However, the polyolefin-based resin in which an anti-blocking agent was added, has been used because the film made of the polyolefin-based resin not containing the anti-blocking agent has an insufficient anti-blocking property, piled films are mutually adhered, and the operability at packaging is lowered.
In place of these finely powdery or fine particle-like inorganic materials, a polyolefin-based resin composition using polymer fine particles as an anti-blocking agent is reported. For example, a polymer fine particles having a particle diameter of 3 to 40 xcexcm and no meting point in JP-A-57-64522, an inert organic polymer crosslinked particles having a weight average particle diameter of 0.5 to 7 xcexcm in JP-A-05-214120, and a polyolefin-based resin composition using particles of a crosslinked polymer, as an anti-blocking agent, obtained by copolymerizing an acrylic monomer and a styrene monomer as main components which has a weight average particle diameter of 0.4 to 7 xcexcm and a film made of the composition in JP-A-06-107868, are reported.
However, although the dispersability of the polymer fine particles as the anti-blocking agent in the polyolefin-based resin was fairly improved compared to that of an inorganic anti-blocking agent such as silica fine particles, to that of the polymer fine particles as the anti-blocking agent in the polyolefin-based resin is not necessarily sufficient, and the polyolefin-based composition contained coagulated matters of the polymer fine particles. When a film is produced by forming into the film from the polyolefin-based composition, there were problems that the coagulated matters are not dispersed, white spots caused by the coagulated matters are generated, the appearance of the film is deteriorated, and points not inked to the film are generated at printing, etc.
The above-described problems have been appeared in accordance with heightening of levels required in film properties.
Under these circumstances, the present inventors have intensively studied and as a result, found that the above-mentioned problems can be solved by using a polyolefin-based resin composition prepared by melt-kneading a polyolefin-based resin with polymer fine particles, as an anti-blocking agent, containing a specific quantity of a volatile component thereby to complete the present invention.
An object of the present invention is to provide a process for producing a polyolefin-based resin composition being able to provide a polyolefin-based resin film which has a good dispersion of polymer fine particles as an anti-blocking agent in a polyolefin-based resin, and is good in appearances such as transparency, see-through feeling, little generation of white spot (occasionally called as fish eye) and the like, and in anti-blocking property and the like.
Namely, the present invention relates to a process for producing a polyolefin-based resin composition, which comprises melt-kneading 100 parts by weight of a polyolefin-based resin (A) and not less than 0.05 parts by weight and less than 2 parts by weight of a polymer fine particles (B) containing 0.10 to 90% by weight of a volatile component, as an anti-blocking agent, and further, to a film made of the above-mentioned polyolefin-based resin composition.